It is desirable to be able to calcine particulate inorganic materials to obtain certain specific results. For example, it may be necessary or desirable to calcine superconductor precursor powders at a temperature just below the onset of sintering, to avoid sintering the particles together into clumps. Such treatment converts the precursor powders into superconductor powders, which can be used directly in extrusion and similar operations without grinding. In this regard, it is known that holding a superconductor fragment at a certain high temperature tends to improve the purity of the superconducting phase and/or to increase the amount of superconducting phase.
It is difficult to calcine many inorganic powders without causing the powders to clump, a result that may require regrinding afterwards. Yet for many purposes it is desirable that the powders be calcined without clumping or agglomeration. For example, it may be desirable to calcine a powder in a controlled atmosphere (of nitrogen, air, oxygen, etc.) in the case that a component of the atmosphere needs to react chemically with the powder. Reaction is faster if the material remains in powder form throughout calcining because of the larger exposed external surface area. However, in such cases, thin beds may be required to get good gas-solid contact. The instant invention renders such measures unnecessary.